I tried sand a few times and had one heck of a time trying to keep my temps stable. I'm no rocket scientist by any stretch of the imagination nor do I classify myself as a pro with the WSM but it's my opinion that sand, though a pretty good shield, isn't much of a heat sink. Sand will block the heat for awhile but will continue to absorb the heat until the mass of the sand hits the same temp of the heat source below and then realeases it so sand will continue to release heat even if the fire goes down and then will slowly cool until it matches the temp of the heat source I don't think there is anything you can do to bring the temp down faster except expose the sand to a considerably cooler surroundings. I guess you'd have to slowly bring your temp up to where you want it but because you don't really know just how much heat your sand has absorbed it's harder to get a true feeling for the actual temp and you end up roller coasting, the best solution I'd think is to use less sand in the pan so it absorbs the heat faster and releases it and cools quicker, of course this is just my .02 worth, many people use sand with no issues what so ever but for me it's a no go. As for the vents, experiment a little trying what works well for others to see whats works best for you. Myself I start with all vents open until I get to with in 30 degrees of my target temp and close one vent completely useally the one facing the wind and by the time I'm finished adjusting the vents I usually have 2 completely closed and the 3rd which I place opposite of the lid vent maybe open a 3rd of the way. This is just what eventually worked out best for me.
